29  * without the usual one-word header. Value is split into 15-bit words,
38  * with 15 bits in each word (the top bit of each word should be 0,
56 		cc = (aw >> 15) & 1;  in cond_negate()
110  *   a <- (a*pa+b*pb)/(2^15)
111  *   b <- (a*qa+b*qb)/(2^15)
118  * Factors pa, pb, qa and qb must be at most 2^15 in absolute value.
138 		 *   |pa| <= 2^15  in co_reduce()
139 		 *   |pb| <= 2^15  in co_reduce()
140 		 *   0 <= wa <= 2^15 - 1  in co_reduce()
141 		 *   0 <= wb <= 2^15 - 1  in co_reduce()
144 		 *   |za| <= (2^15-1)*(2^16) + (2^16-1) = 2^31 - 1  in co_reduce()
157 		tta = za >> 15;  in co_reduce()
158 		ttb = zb >> 15;  in co_reduce()
173  *   a <- (a*pa+b*pb)/(2^15) mod m
174  *   b <- (a*qa+b*qb)/(2^15) mod m
176  * m0i is equal to -1/m[0] mod 2^15.
178  * Factors pa, pb, qa and qb must be at most 2^15 in absolute value.
219 		tta = za >> 15;  in co_reduce_mod()
220 		ttb = zb >> 15;  in co_reduce_mod()
249 	 * a, b, u and v, with the following invariants:  in br_i15_moddiv()
252 	 *   b * x = y * v mod m  in br_i15_moddiv()
259 	 *   v = 0  in br_i15_moddiv()
264 	 *   - Otherwise, if b is even, then b <- b/2 and v <- v/2 mod m.  in br_i15_moddiv()
265 	 *   - Otherwise, if a > b, then a <- (a-b)/2 and u <- (u-v)/2 mod m.  in br_i15_moddiv()
266 	 *   - Otherwise, b <- (b-a)/2 and v <- (v-u)/2 mod m.  in br_i15_moddiv()
270 	 * The result of the modular division is then u (or v: both are  in br_i15_moddiv()
287 	 *   a' = (a*pa + b*pb) / (2^15)  in br_i15_moddiv()
288 	 *   b' = (a*qa + b*qb) / (2^15)  in br_i15_moddiv()
305 	uint16_t *a, *b, *u, *v;  in br_i15_moddiv()  local
308 	len = (m[0] + 15) >> 4;  in br_i15_moddiv()
312 	v = b + len;  in br_i15_moddiv()
315 	memset(v, 0, len * sizeof *v);  in br_i15_moddiv()
332 		 * (a[j] << 15) + a[j - 1], and (b[j] << 15) + b[j - 1].  in br_i15_moddiv()
366 		a_hi = (a0 << 15) + a1;  in br_i15_moddiv()
367 		b_hi = (b0 << 15) + b1;  in br_i15_moddiv()
377 		 * such that a' and b' are both multiple of 2^15, but are  in br_i15_moddiv()
384 		for (i = 0; i < 15; i ++) {  in br_i15_moddiv()
449 		co_reduce_mod(u, v, len, pa, pb, qa, qb, m + 1, m0i);  in br_i15_moddiv()
454 	 * the GCD. If a is 0, then u is 0 as well, and v contains  in br_i15_moddiv()
459 	u[0] |= v[0];  in br_i15_moddiv()
462 		u[k] |= v[k];  in br_i15_moddiv()